This invention relates to oil well equipment and particularly to a cementing tool which is connected to a conventional perforating gun.
In conventional drilling operations, a gun perforater is used to perforate the casing in order to produce oil and/or gas at a specific depth. However, after a period of time has elapsed, gas in commercial quantities may no longer be available for production from the formation and it may be desirable to completely seal the area perforated and to perforate the casing at some point above the sealed area in the hope of realizing oil andor gas production from another zone.
To achieve a strong, high pressure seal, cement is pumped into the casing to seal the perforated area. To achieve the best seal, it is necessary to again perforate the area previously perforated to make larger and more numerous holes in the casing which facilitates the flow of cement into the area immediately around the perforated area both inside and outside of the casing.
Prior to the present tool being developed, it was necessary to run a gun perforater down a wire line to re-perforate the area to be sealed. After the re-perforation, the perforating gun was pulled out of the hole and another string of pipe was run in to force cement into the area which was desired to be sealed. Such an operation was costly and time consuming.
The following patents are relevant because they show methods and apparatus for effecting a dual completed well and various perforating devices and methods: U.S. Pat. Nos. 3,706,344; 3,450,203; 2,970,647; 2,876,843; 2,760,408; and 2,307,360.